This invention relates to communication networks, but more specifically to a network controller and method that enables bearer format negotiation between interfaces of the network in order to facilitate communications between endpoints that support different transmission protocols.
Data transfers occur over channels of communication networks under various transmission protocols, either circuit-based or packet-based. An example of a circuit-based transmission protocol is Time Division Multiplex (TDM). In a TDM protocol, a data stream is conveyed over a physical carrier at a constant bit rate with appropriate framing bits to enable synchronized detection of data. Packet-based transmission protocols, on the other hand, include Internet Protocol (IP) and Asynchronous Transfer Mode (ATM). ATM provides connection-oriented transport of data in fixed-length 53-byte cells while IP provides connectionless transport of data in variable length packets. Either protocol may be used to transport a bearer channel for multimedia, voice, video, or other real-time traffic.
A problem occurs when the bearer channel is passed between networks, or between endpoints and networks, that use different transmission protocols. If an originating endpoint or node connects to a network via an IP interface, and the network uses ATM in its backbone, and the terminating endpoint or node connects to the network via a TDM interface, then conversions must take place between the different transmission protocol types in order for the endpoints to communicate with one another. Further, when one network using one bearer format connects to another network using another bearer format, any communication channel passing between the networks must encounter a conversion between bearer formats.
There are numerous ways to handle this situation. One way involves providing parallel backbone networks for each type of transmission protocol, as well as gateways between the parallel networks to allow endpoints on different networks to intercommunicate. Each parallel network need only have a compatible interface to the other networks and endpoints that use the same bearer format. For example, multiple IP networks can easily interface to other networks and endpoints using IP as their bearer format. A gateway, on the other hand, may be required to interconnect, for example, an ATM-based network and a TDM-based network. Interconnecting incompatible networks via a gateway, while workable, has serious disadvantages. First, it is capital intensive, since multiple network types are deployed. Second, it is operationally complex since each network must be administered independently from one another.
In view of the foregoing, an objective of the present invention is to provide a network controller and method thereof that permit network access via multiple bearer formats.
It is another objective to enable a single-protocol network, such as ATM, that interconnects with networks or nodes that use other transmission protocols.
Another objective of the present invention is to provide a method of format conversion that enables end-users to choose a format that is most appropriate for their needs and equipment capabilities.
It is yet a further objective of the present invention to enable a network to lessen loads on network resources (e.g., reduced processing power, terminations, operations processes, etc.) while performing the required functions.